The present invention relates in general to fuel volume regulating devices for self-igniting internal combustion engines, and in particular it relates to a regulating device of the type which includes a plurality of sensors for sensing operational parameters of the engine, particularly of the actual fuel dosing and of the actual rotary speed of the engine, a control circuit for producing desired values of the operational parameters of the engine, a comparator for comparing the actual and desired values, and an electronic regulating circuit for the adjuster.
A motor vehicle, due to the elastic suspension of its engine and its gears, represents an oscillatory system which, when exposed to an interference such as for example a jump in the amount of injected fuel in the fuel control device of the engine or due to momentary shocks caused by ambient conditions (holes in the roadway), may be excited to more or less strong oscillations. The frequency of such oscillations is usually between 1 to 8 cycles per second and is sensed as jerking. This jerking movement causes changes in the rotary speed of the engine or relative movement between the engine and the car body.
In electronic injection systems for diesel engines, data such as the position of the accelerator pedal, the rotary speed of the engine, and the like information required for dosing or measuring the volume of fuel, are acquired from a control device. The desired value U.alpha.soll of the fuel volume computed by the control device in the first course is adjusted on the fuel injection pump by means of a fuel volume adjuster. An electronic sensing system detects signals corresponding to actual operational parameters of the engine, which are processed and applied via suitable delay lines in the adjuster of the regulating circuit. These sensors, however, render the regulating circuit instable or prone to oscillations, which in turn cause again the jerking movements.
In the U.S. Pat. No. 4,345,559 a device for damping jerking oscillations in an internal combustion engine is disclosed. The damping is accomplished in such a manner that regulating oscillations are derived via a differentiating stage from the rotary speed of the engine, and at certain operational characteristics the engine is fed with counteracting control values which neutralize the jerking movements. This counter-control is effected at the frequency of the jerking oscillations and is dependent on the propagation time of the system. This known device makes it possible to achieve a relatively effective damping of the jerking oscillations; nevertheless, it necessitates extremely high expenditures for circuit elements and/or the signal-processing circuitry.